U2111

Code

OPEL U — Network/User

CAN-Bus No Communication with EPS (Electrical Power Steering)

Brand: OPEL

Type: U — Network/User

Views: UK: 4 EN: 7 RU: 5

AI status

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Page language: EN

Causes

Faulty EPS control module
Open, shorted or damaged CAN bus wiring (CAN High / CAN Low) between EPS and network
Poor power supply or ground to EPS (blown fuse, bad connector, corroded ground)
Failed CAN transceiver inside EPS
Missing or wrong bus termination (open/missing 60 ohm termination or short)
Intermittent connection (corrosion, moisture, broken wires, damaged pins)

Symptoms

EPS warning lamp or EPS fault message displayed
Loss of electric power steering assist or reduced/erratic assist (heavy steering at low speed)
Related systems may show faults (stability/ABS/airbag warnings) or degraded functionality
Steering torque/assist may drop to emergency mode
Intermittent faults or multiple network communication warnings on instrument cluster

What to check

Scan all modules and record freeze frame, freeze data and additional DTCs
Check battery voltage (key on and engine off) and test battery health
Inspect and reseat connectors at EPS and any intermediate junctions
Check fuses and relays supplying EPS power and ignition feed
Measure CAN bus voltages at EPS connector: CAN H, CAN L and differential
Measure termination resistance between CAN H and CAN L (expected ≈ 60 ohms total)

Signal parameters

Recessive (idle) voltage: CAN H ≈ 2.5 V, CAN L ≈ 2.5 V (both near mid-rail)
Dominant state: CAN H rises (≈ 3.5–4.5 V) and CAN L falls (≈ 0.5–1.5 V); differential ~2 V
Termination resistance: typically ~60 ohms measured between CAN H and CAN L with power off
Typical CAN message heartbeat from EPS: periodic messages/heartbeat on the order of 10–100 ms (varies by model)
Common bus data rates for chassis networks: 250 kbps or 500 kbps (confirm factory spec)

Diagnostic algorithm

Connect a capable diagnostic scan tool. Read and save all U-codes and related module DTCs and freeze-frame data.
Note when the fault is set (ignition on, engine on, during driving) and whether fault is permanent/intermittent.
Verify battery voltage and charging system. Low voltage can block module wakeup and communication.
Inspect EPS power and ground circuits: check fuses, relays, and measure supply voltage at EPS connector (ignition on).
Visually inspect EPS connectors and harness for damage, moisture, corrosion; repair as necessary.
With ignition on, measure CAN H and CAN L at the EPS connector: verify recessive voltages, differential, and compare to another known-good CAN node.
Measure termination resistance between CAN H and CAN L with battery disconnected; expected ≈ 60 ohms. Look for shorts to chassis or battery.
Use an oscilloscope or CANalyzer to view waveform quality and message traffic. Confirm presence/absence of EPS message IDs/heartbeats.
If bus is healthy but EPS shows no transmit, suspect internal EPS fault. Before replacing, try: cleaning connectors, verifying grounds, and checking for module programming updates.
If replacing EPS module, ensure proper part number, VIN coding/programming and follow manufacturer reflash/coding procedures. Clear codes and road test to confirm repair.
If faults are intermittent, perform wiggle testing and extended road test while monitoring CAN traffic to replicate the issue.

Likely causes

Loose/damaged connector at EPS module or main wiring harness
Blown fuse or lost battery feed to EPS
Short to battery or ground on CAN+ or CAN- near steering column
Failed EPS module CAN transceiver or internal electronics
Open or high-resistance ground at chassis or module

Fault status

⚠️ Status

No communication with the Electric Power Steering (EPS) control unit detected on the vehicle CAN network. The network gateway or other modules are not receiving the expected EPS messages/heartbeat. This may cause loss or reduction of electric steering assist and can activate steering/system warning lamps.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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